Simulation of battery discharge Mimic short by quickly bringing - - PowerPoint PPT Presentation

Technology Overview

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Current Status

Goal: Design abuse tolerant component to prevent rapid failure in the event of collision or other mechanical abuse.

• Implemented component at the cell level

(with minimum impact on the cost and energy density)

• Reduce need for heavy and expensive

battery protection Status: Concept proven in full cell (experiment and modeling). Fabricating early prototypes. Next Technical: Choose best prototype in small full Li-ion cells with abuse tests Next Development: Fund extended effort (2yr.) Identify practical manufacturing. Demonstrate performance with larger batteries and realistic abuse test. Help needed: Partner for component fabrication and Partner for battery assembly.

Lithium Ion Battery with

Integrated Abuse Tolerant Electrode Features

TEAM: Nancy Dudney, Mat. Sci. and Tech. Div., Oak Ridge National Lab, njdudney@ornl.gov (865)576 4874 ORNL: Michael Naguib, Srikanth Allu, Srdjan Simunovic, Jianlin Li, and Hsin Wang GM: Mei Cai, Mahmoud Abdelhamid, Fang Dai

Project Statistics

Award Amount $450,000 Award Timeline July, 2014 – June, 2015 Next Stage Target Phase 1, $4M over 2 year Collaborations Sought

• materials fabrication
• battery assembly & testing

Isolate the damage upon impact

• Limit the current
• Limit the heat
• Minimize damage
• Maintain partial

function – to drive home

Concept - mechanically damaged area of battery is separated from the rest of cell, isolating potential short circuits.

2

• Crushed or penetrated area of battery

is isolated from the remaining capacity.

► limit current through short ► limit local heating, avoid thermal runaway ► minimize added cost, added weight ► maintain good performance and reliability

• Baseline battery

► pouch single layer (63 mAh) ► LiNi0.5Mn0.3Co0.2O2 (532)/ graphite ► electrolyte LiPF6(DEC+EC)

1 2 3 4 50 100 150 200 Voltage profile of formation cycles from a full coin cell

Voltage_C1 (V) Voltage_D1 (V) Voltage_C2 (V) Voltage_D2(V)

Voltage (V) Capacity (mAh/g)

Proof of concept - abuse tolerant electrode

Compare standard and modified batteries Large single layer vacuum sealed pouch of LMNC vs graphite

• Use steel dart for internal short circuit
• Monitor temperature (IR camera) and OCV (battery tester)

cathode standard anode

• bservation modified

battery standard (63 mAh) OCV for internal short slow discharge; <10mV after 5 hours 0 volts when shorted ∆ Tmax for internal short 2°C at 4 sec 19°C at 3 sec

OCV OCV

cathode modified anode

1.0 sec after shorting with steel dart dart dart Modified battery Standard battery

Proof of concept - abuse tolerant electrode

Compare standard and modified batteries

27.6 ° 35.0° 23.1 ° 23.0 °

Simulation of battery discharge

• Mimic short by quickly bringing current collectors to the same

potential, in this case each to 1.2V vs Li.

5

colors represent Li content

anode cathode

• Isolated area of modified battery shows no

discharge at 10 sec.

• Realistic current upon short

Li Concentration  distance  time (sec)  current (C-rate) 

simulation

0.4 0.8 1.2 1.6 1 2 3 4 58 60 62 64 66 68 70

Current, A Volt Time, s

experiment

Fully charged cell

next to, but isolated from shorted area

Test prototypes of abuse tolerant electrodes

• Impact testing of dry cells

– Simple tests with external battery – Three prototype designs tested to date – Single cell, electrodes and separator, no electrolyte

• Drop test of large ball

against smaller metal or ceramic ball

• Next steps

– Alternate designs and Gen-2 prototypes – Stacked layers for multi- cell battery evaluation

electrode design battery fabrication impact test standard shorted modified1 (engineer

current electrode)

easier to implement Gen1 shorted modified 2

(replace component)

likely impractical damage isolated modified 3

(low cost additive)

possible damage isolated

3V

1 Ω

Status at 6 months - summary

• Major accomplishments
• Established proof of concept with full batteries
• Reduced current and heat from internal short, but not fully isolated.
• Developed analytical model specific for our concept
• Fabricated early prototypes of the abuse tolerant component
• Lessons learned
• Proof of concept was more complex than anticipated.
• Mechanism preventing full isolation has not been identified.
• Experimental scope for remaining 6 months
• Evaluate alternative abuse-tolerant component design
• Test in dry multi-cell stack
• Incorporate into full Li-ion battery
• Program goal – extend R&D (2 years), lead to commercial product
• Collaborations for R&D – component fabrication, battery assembly